CN115795230A - Full-state frequency tracking method and system of piezoelectric transducer - Google Patents
Full-state frequency tracking method and system of piezoelectric transducer Download PDFInfo
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- CN115795230A CN115795230A CN202211287224.6A CN202211287224A CN115795230A CN 115795230 A CN115795230 A CN 115795230A CN 202211287224 A CN202211287224 A CN 202211287224A CN 115795230 A CN115795230 A CN 115795230A
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/11—Complex mathematical operations for solving equations, e.g. nonlinear equations, general mathematical optimization problems
- G06F17/12—Simultaneous equations, e.g. systems of linear equations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
Abstract
The invention discloses a method and a system for tracking the full-state frequency of a piezoelectric transducer, wherein the method comprises the following steps: constructing a relational expression of the voltage and current phase difference of the transducer and the wave-emitting frequency of the transducer based on a Meisen equivalent model; acquiring a wave-transmitting frequency and a corresponding voltage and current phase difference value of the transducer, and solving a relational expression to obtain a solution of the relational expression; judging whether the transducer has a resistive point or not according to the solution of the relational expression; judging that a resistive point exists, and calculating the resonance frequency and the anti-resonance frequency of the transducer; judging that no resistive point exists, and calculating a minimum capacitive point of the transducer; the resonant frequency or antiresonance of the transducer is selected as the varying target value according to the user's requirements. The system comprises: the device comprises a relational expression building module, a relational expression solving module, a judging module and an output module. The invention can be widely applied to the field of transducer tracking control as a full-state frequency tracking method and a full-state frequency tracking system of the piezoelectric transducer.
Description
Technical Field
The invention relates to the field of transducer tracking control, in particular to a full-state frequency tracking method and system of a piezoelectric transducer.
Background
At present, ultrasonic waves can generate mechanical effect, cavitation effect, chemical effect and thermal effect, and are widely applied to the fields of cleaning, detection, processing, welding and the like. The ultrasonic power supply is a core component of an ultrasonic wave generation system, and aims to generate alternating current with specific frequency so that a piezoelectric transducer works in a resonance state. The resonant frequency of the piezoelectric transducer is affected by the load and the driving voltage, and tends to change nonlinearly with time during operation. Therefore, the frequency tracking technology is one of the key technologies of the ultrasonic power supply. In the case of a transducer under a large load, a non-resistive point condition occurs. A method of frequency tracking that can simultaneously adapt both non-resistive and resistive points of a piezoelectric transducer is called the all-state frequency tracking method.
Disclosure of Invention
In order to solve the above technical problems, an object of the present invention is to provide a method and a system for tracking full-state frequency of a piezoelectric transducer, which can be adapted to a resonant frequency and an anti-resonant frequency simultaneously, and have self-resetting and full-state frequency tracking capabilities for mis-tracking.
The first technical scheme adopted by the invention is as follows: a method of full-state frequency tracking of a piezoelectric transducer, comprising the steps of:
constructing a relational expression of the voltage and current phase difference of the transducer and the wave-emitting frequency of the transducer based on a Meisen equivalent model;
acquiring a wave-transmitting frequency and a corresponding voltage and current phase difference value of the transducer, and solving a relational expression to obtain a solution of the relational expression;
judging whether the transducer has a resistive point or not according to the solution of the relational expression;
judging that a resistive point exists, and calculating the resonance frequency and the anti-resonance frequency of the transducer;
judging that no resistive point exists, and calculating a minimum capacitive point of the transducer;
the resonant frequency or antiresonance of the transducer is selected as the varying target value according to the user's requirements.
Further, still include:
and post-processing the change target value according to the set tracking speed and tracking precision.
Further, the relation formula of the transducer voltage and current phase difference and the transducer wave-emitting frequency is as follows:
further, the judgment rule in the step of judging whether the transducer has a resistive point according to the solution of the relation is as follows:
when K is 2 2 -4K 1 K 3 The resistance point of the transducer is larger than or equal to 0 currently;
when K is 2 2 -4K 1 K 3 <0, the transducer currently has no resistive spot.
Further, the calculation formula of the resonance frequency and the anti-resonance frequency of the transducer is as follows:
in the above formula, f r Representing the resonance frequency, f a Representing the anti-resonance frequency.
Further, the calculation formula of the minimum capacitive point of the transducer is as follows:
in the above equation, f represents the minimum capacitive point of the transducer.
Further, the step of performing post-processing on the change target value according to the set tracking speed and tracking accuracy specifically includes:
setting a maximum step value, a steady-state jitter value and a jitter phase difference value;
judging that the voltage and current phase difference value of the transducer is smaller than the jitter phase difference value, and adjusting the target value of the next step to be the sum of the steady-state wave-sending frequency and the steady-state jitter value;
when the voltage and current phase difference value of the energy converter is judged to be larger than the jitter phase difference value and the difference between the next target value and the current wave-sending frequency is judged to be smaller than the maximum step value, outputting a change target value;
and outputting the maximum step value when the voltage and current phase difference value of the energy transducer is judged to be larger than the jitter phase difference value and the difference between the next target value and the current wave-sending frequency is judged to be larger than the maximum step value.
The second technical scheme adopted by the invention is as follows: a full-state frequency tracking system for a piezoelectric transducer, comprising:
the relational expression building module is used for building a relational expression between the voltage and current phase difference of the transducer and the wave frequency of the transducer based on the Meisen equivalent model;
the solution module is used for obtaining the wave-transmitting frequency and the corresponding voltage and current phase difference value of the transducer and solving the relational expression to obtain the solution of the relational expression;
the judging module is used for judging whether the transducer has a resistive point according to the solution of the relational expression; judging that a resistive point exists, and calculating the resonance frequency and the anti-resonance frequency of the transducer; judging that no resistive point exists, and calculating a minimum capacitive point of the transducer;
and the output module is used for selecting the resonant frequency or the anti-resonance of the transducer as a change target value according to the requirement of a user.
The method and the system have the beneficial effects that: the invention has the capability of error tracking and self resetting, and can well solve the problem of frequency error tracking; meanwhile, various oscillators and application scenes are self-adapted, a tracking target can be selected simply, a complicated parameter debugging process of PID (proportion integration differentiation) is not needed, the tracking speed is high, and the precision is high; the control of the transducer under the non-resistance point state can be adapted, and the full-state control of the transducer is realized.
Drawings
FIG. 1 is a flow chart of the steps of a method of full state frequency tracking of a piezoelectric transducer of the present invention;
FIG. 2 is a Meisen equivalent circuit diagram of a full-state frequency tracking method of a piezoelectric transducer of the present invention;
FIG. 3 is a characteristic frequency diagram of the piezoelectric transducer of the present invention;
FIG. 4 is a process flow diagram of a method of full-state frequency tracking of a piezoelectric transducer of the present invention;
fig. 5 is a block diagram of a full-state frequency tracking system of a piezoelectric transducer according to the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and the specific embodiments. For the step numbers in the following embodiments, they are set for convenience of illustration only, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.
As shown in fig. 1, the present invention provides a method for full-state frequency tracking of a piezoelectric transducer, the method comprising the steps of:
s1, constructing a relational expression of voltage and current phase difference of the transducer and wave-emitting frequency of the transducer based on a Meisen equivalent model;
s2, acquiring a wave-transmitting frequency and a corresponding voltage and current phase difference value of the transducer, and solving a relational expression to obtain a solution of the relational expression;
specifically, three unknown numbers of a phase difference-wave frequency relation are solved according to three different wave frequencies and corresponding transducer voltage and current phase difference values, wherein the relation is specifically as follows:
referring to FIG. 2, in the formula，L 1 Is the dynamic inductance, R, of the transducer 1 Being dynamic resistance of the transducer, C 1 Is the dynamic capacitance of the transducer, C 0 Tan theta is the tangent value of the voltage-current phase difference angle of the transducer, and omega is the current working frequency of the transducer.
The system of equations to be solved is specifically:
wherein ω is 1 、ω 2 、ω 3 、tanθ 1 、tanθ 2 、tanθ 3 The last triple wave frequency and the corresponding transducer voltage current phase difference value, the known values in the equation set,
is three unknowns to be solved, and for the convenience of expression, K is used 1 、K 2 、K 3 Instead of the three unknowns.
S3, judging whether the transducer has a resistive point or not according to the solution of the relational expression, calculating the resonant frequency and the anti-resonant frequency of the transducer when the resistive point exists, and calculating the minimum capacitive point of the transducer when the resistive point does not exist;
the specific criteria for whether the transducer has a resistive point at this time are:
K 2 2 -4K 1 K 3 if the result of (a) is greater than 0, this indicates that the transducer now has a resistive spot, otherwise this indicates that the transducer now does not have a resistive spot.
The specific formula for calculating the resonant frequency of the transducer is as follows:
the specific calculation formula of the anti-resonance frequency of the transducer is as follows:
the specific calculation formula of the transducer minimum capacitive point is as follows:
s4, when a resistive point exists, selecting the resonance frequency or the anti-resonance of the transducer as a change target value according to the requirement of a user, and when the resistive point does not exist, using the minimum capacitive point as the change target value;
specifically, whether the tracking target is the resonance frequency or the antiresonance frequency of the transducer is selected according TO requirements, and the calculated value of the resonance frequency or the antiresonance frequency is used as the change target value TO of the next step according TO the selection.
And the control of the transducer under the state of no resistance point is adapted through the judgment of the newly added resistance point.
S41, ordering T according to the tracking target O Equal to the resonant frequency or anti-resonant frequency;
in particular, with reference to fig. 3, the resonance frequency f r Or antiresonance frequency f a The point at which the two reactances of the piezoelectric transducer are 0 is chosen according to the application requirements. In general, medium to low load ultrasonic machining application scenario selection f r Application scenario selection for heavy loads f a 。
S42, calculating T O The absolute value of the difference from the last launch frequency Δ ω.
Specifically, the gain effects of steps S1-S4 are that the tracking target can be selected relatively simply, the complicated parameter debugging process of PID is not required, the tracking speed is fast, and the accuracy is high.
And S5, post-processing the change target value according to the set tracking speed and tracking precision.
S51, setting a maximum step value, a steady-state jitter value and a jitter phase difference value;
specifically, the maximum step size value may be a static value or a dynamic value, and is used to limit the maximum step size of the single step of the algorithm; the adjustment of each step of the algorithm is a steady-state jitter value, and the steady-state jitter value and the jitter phase difference value can be static values or dynamic values.
S52, calculating whether the current phase difference is lower than a set threshold, if so, changing the target value of the next adjustment into: steady state launch frequency + steady state jitter value n% 3, where n is the number of frequency changes since the algorithm began running. Otherwise, the next judgment is carried out.
Specifically, the combination of step S52 and the preceding calculation formula provides the capability of self-reset by mis-tracking.
And S53, if the delta omega is larger than the set maximum step value, directly outputting the initial target value if the delta omega is larger than the set maximum step value, otherwise, directly outputting the maximum step value.
Specifically, fig. 4 is a block diagram of a full state tracking method implementation, wherein preparation steps are performed from the beginning to the calculation of Wc in order to obtain the first three frequency points and phase values. Fig. 1 shows specific steps of Wc calculation, i.e., a calculation result Wc, where a resonance/antiresonance point selected by a user, and processing steps following Wc in a block diagram are post-reaction processing.
As shown in fig. 5, a full-state frequency tracking system of a piezoelectric transducer includes:
the relational expression building module is used for building a relational expression between the voltage and current phase difference of the transducer and the wave frequency of the transducer based on the Meisen equivalent model;
the solution module is used for acquiring the wave-transmitting frequency and the corresponding voltage and current phase difference value of the energy converter and solving a relational expression to obtain a solution of the relational expression;
the judging module is used for judging whether the transducer has a resistive point according to the solution of the relational expression; judging that a resistive point exists, and calculating the resonance frequency and the anti-resonance frequency of the transducer; judging that no resistive point exists, and calculating the minimum capacitive point of the transducer;
and the output module is used for selecting the resonant frequency or the anti-resonance of the transducer as a change target value according to the requirement of a user.
The contents in the above method embodiments are all applicable to the present system embodiment, the functions specifically implemented by the present system embodiment are the same as those in the above method embodiment, and the beneficial effects achieved by the present system embodiment are also the same as those achieved by the above method embodiment.
A full-state frequency tracking device of a piezoelectric transducer comprises:
at least one processor;
at least one memory for storing at least one program;
when executed by the at least one processor, cause the at least one processor to implement a method of full-state frequency tracking of a piezoelectric transducer as described above.
The contents in the method embodiments are all applicable to the device embodiments, the functions specifically implemented by the device embodiments are the same as those in the method embodiments, and the beneficial effects achieved by the device embodiments are also the same as those achieved by the method embodiments.
A storage medium having stored therein instructions executable by a processor, the storage medium comprising: the processor-executable instructions, when executed by the processor, are for implementing a full-state frequency tracking method for a piezoelectric transducer as described above.
The contents in the above method embodiments are all applicable to the present storage medium embodiment, the functions specifically implemented by the present storage medium embodiment are the same as those in the above method embodiments, and the advantageous effects achieved by the present storage medium embodiment are also the same as those achieved by the above method embodiments.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. A full-state frequency tracking method of a piezoelectric transducer is characterized by comprising the following steps:
constructing a relational expression of the voltage and current phase difference of the transducer and the wave-emitting frequency of the transducer based on a Meisen equivalent model;
acquiring a wave-transmitting frequency and a corresponding voltage and current phase difference value of the transducer, and solving a relational expression to obtain a solution of the relational expression;
judging whether the transducer has a resistive point or not according to the solution of the relational expression;
judging that a resistive point exists, calculating the resonant frequency and the anti-resonant frequency of the transducer, and selecting the resonant frequency or the anti-resonant frequency of the transducer as a change target value according to the user requirement;
and judging that the resistive point does not exist, calculating a minimum capacitive point of the transducer and taking the minimum capacitive point as a change target value.
2. The method of claim 1, further comprising:
and post-processing the change target value according to the set tracking speed and tracking precision.
3. The full-state frequency tracking of the piezoelectric transducer according to claim 2, wherein the relationship between the transducer voltage-current phase difference and the transducer wave frequency is expressed as follows:
in the above formula, L 1 Presentation tradeDynamic inductance of energy devices, R 1 Representing the dynamic resistance, C, of the transducer 1 Representing the dynamic capacitance, C, of the transducer 0 The static capacitance of the transducer is represented, tan theta represents the tangent value of the voltage-current phase difference angle of the transducer, and omega represents the current working frequency of the transducer.
4. The method for full-state frequency tracking of a piezoelectric transducer as claimed in claim 3, wherein the determining rule of the step of determining whether the transducer has a resistive point according to the solution of the relation is as follows:
when K is 2 2 -4K 1 K 3 The resistance point of the transducer is larger than or equal to 0 currently;
when K is 2 2 -4K 1 K 3 <0, the transducer currently has no resistive spot.
5. The method of claim 4, wherein the resonant frequency and anti-resonant frequency of the piezoelectric transducer are calculated as follows:
in the above formula, f r Representing the resonance frequency, f a Representing the anti-resonance frequency.
6. The method of claim 5, wherein the minimum capacitive point of the transducer is calculated as follows:
in the above formula, f l Representing the point of minimum capacitance of the transducer.
7. The method for full-state frequency tracking of a piezoelectric transducer according to claim 6, wherein the step of post-processing the target value of the change according to the set tracking speed and tracking accuracy comprises:
setting a maximum step value, a steady-state jitter value and a jitter phase difference value;
judging that the voltage and current phase difference value of the transducer is smaller than the jitter phase difference value, and adjusting the target value of the next step to be the sum of the steady-state wave-sending frequency and the steady-state jitter value;
when the voltage and current phase difference value of the energy converter is judged to be larger than the jitter phase difference value and the difference between the next target value and the current wave-sending frequency is judged to be smaller than the maximum step value, outputting a change target value;
and outputting the maximum step value when the voltage and current phase difference value of the energy transducer is judged to be larger than the jitter phase difference value and the difference between the next target value and the current wave-sending frequency is judged to be larger than the maximum step value.
8. A full-state frequency tracking system for a piezoelectric transducer, comprising:
the relational expression building module is used for building a relational expression between the voltage and current phase difference of the transducer and the wave frequency of the transducer based on the Meisen equivalent model;
the solution module is used for obtaining the wave-transmitting frequency and the corresponding voltage and current phase difference value of the transducer and solving the relational expression to obtain the solution of the relational expression;
the judging module is used for judging whether the transducer has a resistive point according to the solution of the relational expression; judging that a resistive point exists, and calculating the resonant frequency and the anti-resonant frequency of the transducer; judging that no resistive point exists, and calculating a minimum capacitive point of the transducer;
and the output module is used for selecting the resonant frequency or the anti-resonance of the transducer as a change target value according to the requirement of a user.
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| CN202211287224.6A CN115795230A (en) | 2022-10-20 | 2022-10-20 | Full-state frequency tracking method and system of piezoelectric transducer |
| CN202310364288.XA CN116484155B (en) | 2022-10-20 | 2023-04-07 | Full-state frequency tracking method and system for piezoelectric transducer |
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| AU1983397A (en) * | 1996-02-29 | 1997-09-16 | Acuson Corporation | Multiple ultrasound image registration system, method and transducer |
| CN104252146B (en) * | 2013-06-28 | 2017-11-07 | 东莞华中科技大学制造工程研究院 | The driving method and device of a kind of ultrasonic transducer |
| CN111817711B (en) * | 2020-07-09 | 2024-01-30 | 杭州国彪超声设备有限公司 | Frequency tracking method of ultrasonic processing system |
| CN111596544B (en) * | 2020-07-22 | 2020-10-27 | 四川大学 | Frequency tracking search method based on fuzzy PD |
| CN113934137B (en) * | 2021-10-20 | 2022-07-15 | 江南大学 | Ultrasonic power supply resonant frequency tracking method and system |
| CN114638102A (en) * | 2022-03-15 | 2022-06-17 | 广东工业大学 | Modeling and matching method for high-power piezoelectric transducer |
| CN115102425B (en) * | 2022-07-25 | 2022-12-02 | 上海逸思医疗科技股份有限公司 | Control method of dynamic branch current of ultrasonic transducer and ultrasonic surgical system |
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